Credit: Jason Nichol
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You're in a public bathroom with clean, dripping hands, standing in front of an electric hand dryer and a paper towel dispenser. What do you do?
There's a huge range of hand dryers on the market, but in all of them the heating element is the main power-sucking culprit - the element in a 2450W hand-dryer, for example, uses 2200W of its power.
Ninety-eight per cent of the global warming potential of an electric dryer and 65 per cent of resource depletion comes from the electricity use during its lifetime.
Short of running tests each time you visit a public toilet, it's difficult to tell which models are using the most energy. Real boffins will even tell you it depends on whether the nozzle spins upwards to dry wet hair!
But on average, the typical public bathroom contains a dryer that uses 0.02 to 0.08 kWh, producing 21 to 85 g of CO2. Hit the button twice and you'll double that.
A tale of two towels
Most of the studies that have been done on this dilemma came out in favour of electric dryers, finding that paper towels use up to 10 times more energy. But then, they were commissioned by electric dryer companies.
They assumed people use two paper towels after they wash their hands. When in actual fact, on average, for both men and women, 1.5 paper towels are used per bathroom visit, according to Jim Bowyer, a professor of bioproduct and bioprocess engineering at the University of Minnesota.
The studies also assumed that paper towels weighs 2.8 to 3.8 g, when most paper towels are actually between 1.97 g and 2.12 g.
When this variation is accounted for, and using energy figures from BuildingGreen, an independent building advisory company, the energy needed to harvest and manufacture a paper towel is 0.07 kWh if the paper is made form virgin fibre, or 0.04 kWh if the towel has recycled content.
So, in fact, the energy use per bathroom visit is about the same no matter which option you choose.
Recycling dead end
Don't be fooled by the utilitarian appearance of paper towels - most aren't made from recycled paper. Office supply company Corporate Express, which sells office and bathroom products to 45,000 clients in Australia and New Zealand, carries only two types of recycled paper towels in the 11 varieties it stocks.
Even if you do use paper towels with recycled content the recycling loop ends after we dry our mitts on them; recycling companies class discarded paper towels as 'contaminated' and add them to general waste.
It seems counterintuitive, but hand dryers have more recycling potential than paper towels. "You could absolutely recycle a hand dryer," says Chris Fisher from metal recycling company CMA. "You'd just take it to a scrap yard."